The invention is directed to a power supply system including a battery, a three-phase generator, and a rectifier connected with the generator and whose voltage is limited by switching on and off the field current of the generator with a voltage regulator that determines the actual voltage of the voltage at the generator terminals and produces an average field current in the generator exciter field.
Conventional built-in regulators for three phase generators maintain constant the voltage at the terminals of the generator. However, the terminals of the battery are also decisive for the voltage of the power supply system. The voltage drop U.sub.R on the line may amount to up to 400 mV. If regulation to the battery voltage is to be effected, an additional line from the battery to the built-in regulator is required.